That exhaust bracket is unsurprising. Lots of Citroen do it. I had exactly the same problem on our C3 Picasso at 3 years. The exhausts last well but the brackets are cheap mild steel . The weld on our car took 5 minutes at my local repairer and MOT tester (not a dealer) was free and five years later has well outlasted the original bracket. Scandalous charge at Robins and Day but take heart some dealers do not offer to weld!